Field of the Invention
The present invention is broadly concerned with novel poly alkanolamine polymers, which find particular utility as petroleum/water emulsion breakers. More particularly, the invention is concerned with such polymers, as well as methods of synthesis thereof, wherein the polymers contain a plurality of different secondary and tertiary alkanolamine moieties. The polymers are synthesized by reacting secondary or tertiary alkanolamines with fatty acids and organic acids.
Description of the Prior Art
An important objective of any oil production facility is the separation of water and other foreign materials from the produced crude. The breaking of these crude oil and water emulsions constitutes a challenging aspect in the oil production industry.
During the productive life of an oil or gas well, a stage is reached when water will be co-produced in unacceptable quantities. This water co-exists with the hydrocarbons in the reservoir and generally infiltrates into the hydrocarbon-bearing regions of the formation. Eventually water becomes a part of the production from the wells regardless of the method of recovery. Secondary or tertiary methods are another cause of water encroachment. These methods are employed to increase the amount of petroleum recovered from the reservoirs, and they may involve many different techniques. Some of these require the injection of water or steam into the reservoirs, which further complicates the emulsion problem.
An emulsion is a mixture of two immiscible liquids, one of which is dispersed as droplets in the other. The liquid of emulsion that is broken into droplets is known as the dispersed or internal phase, whereas the liquid surrounding the droplets is called the continuous or external phase. In the petroleum industry, water-in-oil emulsions (often referred to as “regular” emulsions) are the most frequently encountered. However, oil-in-water emulsions (sometimes known as “reverse” emulsions) are also very common.
A number of techniques have been employed for demulsification or breaking of emulsions, including heating, electrical processes of dehydration, mechanical separation equipment, free-water knockouts, and chemical injection. In many instances, chemical injections are preferred inasmuch as the emulsions are resolved more quickly and effectively than by other techniques; moreover, chemical treatments have a wide range of application and are equally adaptable to large- or small-scale operations.
Poly alkanolamines, such as poly triethanolamine, have been used in the past as reverse emulsion breakers, see U.S. Pat. Nos. 2,407,895, 4,238,330, 4,505,839, 4,731,481, 5,393,463, 5,607,574, RE28,576, and US Patent Publication No. 2010/0234631. Generally speaking, poly alkanolamines are produced by the condensation reaction of alkanolamines at high temperatures using a dehydration catalyst. Advantageously, the product should be slightly cross-linked to obtain optimum emulsion breaking properties. However, these products, while useful, do not provide the most desirable degree of emulsion breaking.
US Patent Publication No. 2008/0214850 describes certain “esterquat” surfactant products made by reacting alkanolamines with C6-C10 monocarboxylic acids and C12-C22 monocarboxylic acids, followed by quaternizing the resulting esters. These products are not polymerized, however. A companion reference, US Patent Publication No. 2008/0214776, describes polymeric “esterquats” wherein the foregoing components, along with one or more dicarboxylic acids, are reacted to form polymers having ester-amine backbones with asymmetric side chains. Polymeric “esterquats” are also disclosed in U.S. Pat. No. 8,474,627.